Method and apparatus for roasting and smelting in a hearth furnace



Aug. 20, 1940. H. R. M QMICHAEL METHOD AND APPARATUS FOR ROASTING AND SMELTING IN A HEARTH FURNACE Original Filed June 21, 1935 7 Sheets-Sheet l n2 Rm IIIII-IIIIIIIIIII! INVENTOR HUGH R MACYVHCHAEL.

ATTORNEY own 35 $332 g- 1 0- H. R. M MICHA'EL 2,211,932

METHOD AND APPARATUS FOR ROASTING AND SMELTING IN A HEARTH FURNACE Original Filed June 21, 1935 7 Sheets-Sheet 5 .l 112- 1 uremj gur' 2-17.

'INVENTOR HUGH R. MACM ICHAEL BY fiwm ATTORNEY Aug. 20, 1940. H. R. M MlCHAEL 2,211,932

METHOD AND APPARATUS FOR ROASTING AND SMELTING IN A HEARTH FURNACE Original Filed June 21, 1955 7 Sheets-Sheet 4 am 196 18m v [96 1- x INVENTOR HUGH RJVIACMICHAEL ATTORNEY Aug. 20, 1940. H R. M MICHAEL 2,211,932

METHOD AND APPARATUS FOR ROASTING AND SMELTIXG IN A HEARTH FURNACE Original Filed June 21, 1935 7 Sheets-Sheet 5 P w BY MM 5 IE3 ATTORNEY H. R. M MlCHAEL Aug. 20, 1940.

METHOD AND APPARATUS FOR ROASTING AND SMELTING IN A HEART FURNACE '7 Sheets-Sheet 6 Original Filed June 21, 1935 wan INVENTOR L E A H m M C A M R H G U H ATTORNEY 7 Aug. 20, 1940. H. R. M MICHAEL 2,211,932

METHOD AND APPARATUS FOR ROASTING AND SMELTING IN A HEARTH FURNACE Original Filed June 21, 1935 7 Sheets-Sheet 7 ATTORNEY Patented Aug. 20, 1940 PATENT OFFICE METHOD AND APPARATUS FOR- ROASTING AND SMELTING IN A HEARTH FURNACE Hugh R. MacMichael, Piedmont, Calif.

Application June 21, 1935, Serial No. 27,697 Renewed July 7, 1939 49 Claims.

This invention relates to the roasting and to the smelting of lead sulphide ores primarily and has for its objects to provide, first, certain improvements in methods whereby high-grade lead 6 ores may be more economically treated, and second, certain improvements in the metallurgical equipment necessitated thereby.

More particularly, from the principles of the well-known Scotch hearth furnace process, it develops a process whereby, with improved equipment, operations are to be conducted in a large automatically-operated furnace, substantially without manual labor, requ'iring extremely little repair, operating at a substantially reduced cost, and requiring a substantially lower cost for plant construction.

Some of the disadvantages of the prior Scotch hearth method are that it remains essentially a manual art laboriously and erratically conducted in small one-man furnaces to and from which all treated materials are manually handled at least twice. Each plant generally requires a considerable number of these small furnaces, and in operation they are open to the atmosphere so that an immense amount of outside air is drawn in and mixes with the furnace gas, and all this resultant diluted gas has to be handled through an enormously expensive baghouse for the recovery of the valuable metallic fumes carried from the furnace with said gas. Some of the other difliculties and inadequacies of the processes and devices of the prior art will be noted later.

One object of my invention is to provide a feasible method of charging a small or an extremely large hearth-type furnace whereby each part of the smelting area of said furnace will receive fresh charge accurately and controllably spread in a thin layer generally forty to fifty times per hour on a predetermined schedule, which result I accomplish by the steps of first forming outside of the furnace the various elements of the charge into a unit charge properly proportioned and properly distributed in a thin layer over an area co-extensive with the smelting area in said furnace, and second, depositing the said formed unit charge in smelting position over the entire smelting area of. said furnace substantially simultaneously. I preferably include the coke-breeze in each charge, instead of adding it irregularly as heretofore. -As a further improvement I prefer to deposit the aforesaid unit charge in the furnace with a controlled spreading effect somewhat simulating the effect in manual charging where the charge on a shovel perhaps a foot square, may be manually spread over several square feet of the furnace. The charge-receiving length of the furnace exceeds the smelting length so that the charge irregularly deposited at each end may be discarded. With the appropriate means which I provide, I effect the described methods of charging with an ideal uniformity of working and smelting results, hitherto continually sought but never attainedin the'charging of the prior art. Another object of my invention is to effect the complete separation from the smelting charge of the lump slag which is agglomerate containing-the slag-forming elements introduced with said charge, and to discard same from the furnace. A characteristic feature of the Scotch hearth smelting is the discarding of a lump slag instead of a molten slag as in other smelting processes, and the final separation and discarding of these lumps, has hitherto been a manual 20 operation. The charge in a hearth furnace tends to cake and to agglomerate as it smelts and has to be broken up about forty times per hour by a rabbling operation in which a poker is passed into the crucible and up through "the overlying 2: smelting charge, the fines of said charge tending to fiow around said poker while the coarser lumps selectively tend to be thrown to the surface and out onto the, apron along the front of said crucible to a position approximately underlying the line 13 of Fig. 37, from which position in the practice of the prior art substantially the entire charge has been backed immediately to its smelting position in area I0 (Fig. 37), which second operation still leaves the coarser lumps selectively accessible to be manually picked out and manually removed from the furnace. I have discovered that by correlating the force and efiect of the rabbling with the width and slope of the apron I28 onto which the rabbled charge is partly displaced, that the coarser lumps may be separated controllably and selectively, and caused to move across said apron, and thereby to be discarded from said furnace. I provide a furnace with its operating equipment which is all suitably correlated in design for the purpose stated, and for the operation of the rabbling poker, I provide a manually-adjustable variablespeed drive. As the throwing force and effect of any movement is substantially proportional to the square of the velocity of said movement, it is then quite feasible to operate the rabbler poker at a speed adjusted to that necessary forzcontrollably discarding the lump slag and at the same time suitably rabbling the charge.

While the amount of the lump slag to be discarded can be controlled with considerable accuracy by the means herein provided, I prefer currently to discard some excess, to pass the entire discard over a suitable screen, and to return the finer screened part to the furnace, and finally to discard the coarser part, which latter will then normally be smelted in a blast furnace with the production of a liquid slag very low in lead and suitable for a final waste product. 4

Another object of my invention is to provide a method for neutralizing a longitudinal shifting tendency of the smelting charge, wherein said charge tends to follow along with the longitudinal movement of the rabbler carriage while the rabbling poker is working in said charge. This shifting tendency takes place even though the rabbler carriage is provided with the so-called step-by-step movement now in common use wherein the rabbler carriage movement is retarded while the rabbling poker is passing up through the charge. With manual backing, the aforesaid shifting tendency was taken care of by the operator in his work of backing and charging the furnace, and with mechanical backing certain expedients were adopted supplemented by manual work. I have discovered that by rabbling the furnace alternately in opposite directions, the longitudinal shifting of the charge is thereby completely neutralized and no other mechanical expedients or manual labor are required in this connection. In order to maintain, by this method, the desired degree of uniformity in the time period between the successive rabblings at all points along the furnace, I find it desirable substantially to reduce the length of the furnace hitherto rabbled by one poker, preferably limiting this distance to about five feet instead of the hitherto customary eight feet. This limitation is decidedly beneficial for a like reason in connection with my method of depositinga unitary charge over the full length of the furnace substantially simultaneously. None of the mechanical rabbling means hitherto available have been adapted either to rabbling alternately in opposite directions, or to rabbling only a short furnacelength with one poker while permitting of reasonable access to said furnace even though it were limited in length to the eight feet hitherto generally used, to say nothing of still longer lengths. I have therefore provided novel rabbling means, and also novel backing means cooperating therewith, for conducting my method of rabbling and of backing, which method has other novel features to be further described.

Another object of my invention relates to a method for conducting a rabbling operation preferably followed concurrently in similar mode by a backing operation, whereby a hearth-type furnace having a length up to one hundred feet or even much longer may be suitably rabbled and backed. For this purpose I use a plurality of rabbler pokers working about five feet apart along the length of the furnace, all said pokers working generally concurrently although not necessarily in unison. I shift these spaced operating pokers about five feet longitudinally relative to said furnace until the spaces intervening between the starting points of the respective pokers in their original positions have been rabbled, and I thus complete a rabbling operation over the entire length of a very long furnace in a very brief space of time, and in like manner the substantially concurrent backing operation is almost simultaneously completed. However, the method as Just specified is adaptable whether the space between adjacent pokers is five feet or very considerably more. The reason threfor for specifying about five feet is (a) to avoid an undue variation in the time between the successive rabblings at each and all points along the length of the furnace, when the rabbling operation progresses alternately in opposite directions along said furnace, and (bl when using the unit charge simultaneously deposited over the length of the furnace, a short rabbling space for each poker is desirable to limit the length of time intervening between the rabbling and the quickly following charging at any point along said furnace. Another object of my invention is to provid a method for substantially limiting the formation of accretions along the back of the furnace crucible at about the level at which the molten metal is normally carried therein. In the prior art the point of the rabbler poker scraped up the back'of the crucible on a series of spaced lines corresponding to the step-by-step position of the rabbler carriage. These steps are generally nearly five inches apart and there is no means for systematically scraping the crucible wall intervening between the spaced positions of the said steps, and therefore from time to time a manual scraping operation is required, in an endeavor to avoid which the operator tends to put too much pressure on the mechanical poker contacting the back wall of said crucible thereby eventually causing the destruction of many crucibles. I have discovered that by causing the aforesaid series of spaced lines of the rabbler poker scraping action against the wall of said crucible, on successive rabbling operations, to be on lines substantially intermediate to the said lines of the preceding rabbling operation, I can keep the crucible in good order without resorting to the periodical manual scraping thereof, and with no temptation on the part of the operator'to cut out said crucible wall by excessive pressure of said poker. I accomplish this by suitably adjusting the starting point of the rabbler carriage travel on successive cycles of rabbling operation, with due regard to the correlation between said travel and the rabbler poker operation as it strokes up the back of the said crucible, the means for systematically doing which is further described herein.

Another object of my invention is to provide methods of operation, and the equipment, whereby the hearth smelting operation may be conducted with the admission of only a relatively small and controlled amount of outside air to the furnace hood thereby first, permitting a very large reduction in the construction cost of the gasfume filtration equipment and other means for handling gas, which items together represent the major source of construction cost in a Scotch hearth-type furnace plant, and second, effecting a reduction in the operating cost for handling said gas. In the prior art, along the operators side of the furnace there is generally a continuous opening about one foot high through which is admitted a large quantity of outside air which mixes with the furnace gases carrying a considerable quantity of metallic fume, thereby necessitating the treatment of all these gases including the infiltrated air for the recovery of said metallic fume, this treatment usually consisting of passing said gases through a woolen cloth filtering medium in so called bag-houses. By my invention, I provide a novel design of furnace and operating means therewith whereby the furnace -may remain substantially closed against unconspective of its length. This smelting process requires a furnace with an elongated crucible which is normally carried substantially level full of molten metal, the level of which should generally be maintained constant within an inch or so. The crucible is continuously, open along one side to permit access of the rabbler and the backer, and if the metal overflows at any point it tends to solidify on the furnace apron I28 and requires manual labor for its removal and rehandling'. If the molten metal level is unduly lowered by drawing oif from the furnace too much metal there is a tendency to form accretions along the back and front of the crucible at approximately the normal level of the molten metal and the operating conditions become unsatisfactory. The mechanical backer 400 is adapted to back and reform the rabbled charge on certain predetermined lines and the relative levels of the hacker and the furnace must be accurately maintained for said operation. The mechanical rabbler 300, in its work of rabbling the smelting charge and limiting accretions on the back wall of the crucible without causing wear thereto, (also performing a somewhat similar service along the front edge of said crucible), must have a furnace maintained in accurate lateral alignment as well as level in working relation with said rabbler. Furnaces with crucibles carrying molten metal are generally limited to a length of about five times their width and generally they warp to a considerable extent. However, as (a), the walls enclosing such smelting furnaces generally continue upward all around the crucible thereof to substantially above the normal level of the molten metal therein, and as (b) they generally do not have mechanical operating means required to work in close and fixed relation with either one or both sides of their crucibles, nor (0) to have a side continuously open just above the molten-metal level for the access of any operating means, the walls of said furnaces and their crucibles can warp laterally and there can also be vertical upheavals both without detriment to the service to be rendered and generally their main requirement is that they continue to hold metal and that the walls and roof do not fall in. For my invention, I prefer a furnace with a length at least ten times its width and preferably at least sixty times the width where the total daily tonnage of ore to be treated thereby is adequate to keep a furnace of this size occupied. Hitherto there has been no metallurgical crucible furnace having anything remotely approaching such ratios of length to width, or the necessity of carrying the molten metal substantially level full along an open side of its crucible, or the necessity for maintaining itself in accurate working relation with other operating means, and having any or all of these requirements combined with a furnace preferably of fifty to one hundred and fifty feet in length, and which must be maintained tight against the leakage of a low melting point metal such as lead which tends to seep interminably through hot masonry or even through otherwise imperceptible passages in cast-iron containers. The means providedfor securing a thoroughly reliable construction to meet these extraordinary requirements with substantially complete freedom from repair is part of my invention.

Another object of my invention is to provide a rabbling device adapted: (it) to rabble uniformly and rapidly a furnace of great length such as one hundred feet more or less; (1)) to cause the coarser lump slag of the smelting charge to be selectively and controllably discarded from the furnace, the rabbler mechanism being provided with a variable-speed drive and the furnace apron I28 having a width and slope all especially adapted for said object; (o) to limit the formation of accretions on the rear wall of the furnace crucible by scraping same on a plurality of series of spaced lines controllably positioned to eifect a substantially longitudinally continuous scraping operation within every few minutes of operating; (1!) to work on any'of the new cycles of rabbler operation herein proposed as well as by any of the modes of the prior art; (e) to accomplish these objects with only a negligible open area into the hood of the furnace through which the rabbling pokers move in their work; (I) to provide a rabbling poker which can work for days without change, as contrasted with the poker of the prior art which rapidly'overheats and commonly has to be changed several times in each hour of operation; and (g) to do all this with a simple rugged construction substantially free of upkeep and repair requirements.

Another object of my invention is to provide a backing device adapted: (a) to cooperate suitably in all respects with the aforesaid rabbling device: (b) to sweep the dead-rplates I38 at each end of the furnace of the surplus charge accumulating thereon from the rabbling and backing operations and also that deposited from the charger 200; (c) to be moved into transposed position relative to the rabbler so that rabbling and backing operations may proceed alternately in opposite directions along the furnace; (d) to perform the backing operation with means extending into the furnace through generally sealed openings thereto; and (e) to do all of this with a simple rugged construction with advantages such as above specified for the rabbler construction.

Another object of my invention is to provide an automatic control system adapted: (a) to control the suitable charging of the furnace; (b) to control the starting and the stopping of any and all of the mechanically conducted operations for the service of said furnace; and (c) to provide adjustable means whereby each operation can be adjustably controlled to give the best results for any of the possibly widely variable operating conditions to be met with in the treatment of different metalliferous ores or materials, each with pos-.

sibly widely varying percentages of differing slagforming elements contained therein, sometimes using different fuels, and all at varying tonnage rates. In the prior art, the controlling means for the rabbling and the backing device generally pro vided only for stopping the same at the end ofa one-way operating movement and also at the end of an idling return movement, the starting of both movements being manually effected. The completely adjustable, accurate and automatic control of a process using a series of inter-related operations, each to be repeated preferably forty to fifty times per hour at each and all points along the furnace, provides advantages obvious to anyone skilled in the art, and especially when contrasted with the practical impossibility of accurate control where arduous manual labor is involved as always present in the art as hitherto practiced.

Another object relates to the substantially complete elimination of the considerable amount of irregular manual labor required on account of the unavoidably disorderly and irregular conditions generally present in the laborious operation hitherto conducted in the smelting practice with a Scotch hearth type of furnace even provided with the best mechanical equipment hitherto available, which object I have accomplished by the substitution of clean, orderly, mechanically conducted operations at all essential points combined with the practical elimination of the nonessential work.

To an important degree this invention relates to improved methods of conducting a roasting and a smelting process on the principles of the well-known Scotch hearth process. In part, these methods may be put into effect on manually operated furnaces or by various sorts of construction or mechanical devices some of which are known in the prior art and some of which might be provided by means varying considerably in detail one from the other. To obtain the full advantage of all the methods which I have described, I have invented a novel hearth type furnace and novel means adapted to the charging, rabbling and backing of said furnace, both the furnace and the means cooperating therewith having many advantages in themselves over anything for the like purpose in the prior art.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

Fig. 1 is a general side elevation of the furnace with its rabbling and backing mechanism, and its charge bins.

Fig. 2 is a side elevation continuing to the right from Fig. 1 showing the extended track under the charger.

Fig. 3 is a general plan of the arrangement corresponding to the side elevation in Fig. 1.

Fig. 4 is a general plan corresponding to the side elevation in Fig. 2.

Fig. 5 is an end elevation showing the furnace in its building looking from the line 55 of Fig. 1.

Fig. 6 is an end elevation looking from the line 6-6 of Fig. 2.

Fig. 7 is a cross section through the rabbler, the backer and the furnace taken on line I1 of Fig. 3.

Fig. 8 is a cross-section through the rabbler and the backer taken on the line 8-8 of Figs. 1, 9 and 11.

Fig. 9 is a. partial plan of the rabbler, as viewed from the line 99 of Fig. 7.

Fig. 10 is an elevation of the rabbler taken on the line Ill-l0 of Fig. 9.

Fig. 11 is a partial side elevation of the backer and the furnace hood (only), as viewed from the line Il-ll of Fig. '7.

Fig. 12 is a cross-section of the backer taken Fig. 17 is a cross-section through the backer main shaft taken on the line l1--|'I of Fig. 16.

Fig. 18 is a cross section through the backer main shaft taken on the line I8-l8 of Fig. 16, but showing the rocker lever 42l rotated for engagement with the trigger 422.

Fig. 19 shows a longitudinal elevation of the furnace and hood partly as viewed on the outside of the line l9l9, and partly in cross section as viewed from the line I9'-l9', both of Fig. 3.

Fig. 20 is a cross-sectional elevation through the furnace and the hood taken on the line 2020 of Fig; 19, and also showing the cross section of the charger when in that location.

Fig. 21 is a cross-sectional plan at one end of the hood taken on the line 2|--2l of Fig. 19, the level of which line is also marked for convenience in Fig. 20.

Fig. 22 is a cross-sectional longitudinal elevation of one end of the hood with part of the charger taken on the line 22-22 of Fig. 21.

Fig. 23 is a partial plan of one end of the furnace taken on the line 23-23 of Fig. 19.

Fig. 24 is a longitudinal cross-section through a charge bin, a feeder and. the charger taken on the line 24--24 of Fig. 25.

Fig. 25 is an end view of the bin and the feeder, and a cross-section of the charger, taken on the line 25-25 of Fig. 24 and also shows the control diagram for the feeder arrangement.

Fig. 26 is a diagrammatic elevation of the furnace and the charging device, showing the relative location of the electric terminals for the charger and the feeder control.

Fig. 27 is a diagrammatic detail of the electric terminal switch for the control of the feeders and the charger.

Fig. 28 is a diagram showing the various relative positions of the furnace, the rabbler and the hacker.

Fig. 29 shows diagrammatically the solenoid operated hydraulic valves used on the cylinder which impart movement to the rabbler and the backer.

Fig. 30 shows diagrammatically the solenoid operated hydraulic valve for speed control.

Fig. 31 is a detailed end elevation of the backer shovel.

Fig. 32 is a. detailed side elevation of the backer shovel.

Fig. 33 is a section through the hacker shovel arm taken on line 3333 of Fig. 32.

Fig. 34 is a detail of the rabbler poker.

Fig. 35 is a cross-section through the rabbler poker taken on the irregular line 35-35.

Fig. 36 is a diagram of the electrical control governing the operation of the rabbler, the backer and the charger.

Fig. 37 is a cross-section taken on the line 1-1 of Fig. 3 similar to that of Fig. '7, and shows various paths of motion and different positions of the smelting charge.

Like reference characters denote like parts in the several figures of the drawings. For convenient reference the various main parts have been given certain groups of numbers as folother end.

Control system--- A to M, 2 to I3, and 49I and up- The building The building 88 (see Figs. 1 and 5) enclosing and in parts supporting the furnace I00 and cer-' tain equipment operating therewith, has the left columns 89 and the right columns carrying the trusses 9| supporting the longitudinal beams 92 and 93 between which are carried a plurality of the cross-beams 94, the trusses also each supporting a hanger carrying one end of the crossbeam 96 supporting one side of the rabble 300' and being supported by the column 89 on the The furnace The furnace I00 has a crucible IOI enclosed by a semi-circular jacket I02 having an inner plate I03, and an outer plate I04 connected by the end flange plates I05 which extend outward and are provided with bolt holes. Along the top of the front of said jacket I02 is the plate I01 extending outward and provided with holes for bolts attaching the apron I28 and also extending inward to keep the brick II4 from being floated out by the molten lead'of the crucible in operation. In like manner the plate I08 forms the top back of said jacket I02 and extends inward for retention of the brick H4 and extends-outward adapted for bolting on the clips I09 for retaining the tuyere jackets I42 in position. The pipes IIO are connected into the front of said jacket I02 and are adapted for the inlet and outlet of circulating water, the pipes III being connected into the back of said jacket I02 for alike purpose, all said pipes being connected very close to the top of the space in said jackets I02 so that air or steam may not be trapped therein to a harmful degree. For a long furnace the jacket I02 may conveniently be made in sections ten to fifteen feet long and bolted together by the flange plates I05. At each end of the crucible is an end plate II2 bolted to a flange I05 of the adjacent jacket I02 and adapted to support a spout II3 through which the molten metal may be tapped from the crucible ml. The crucible is provided with a longitudinal brick lining I I4 and near each end are the bridge walls II5 with the-passage I I6 leading to the spout I I3. At each end of the crucible IOI a brick lining III is prevented from being floated out by an angle II8 attached to the end plate II 2. At about the middle of its length the crucible IOI is firmly supported by the A frame I22 and it has additional spaced supports I23 with the diagonal bracing I24 flrmly supporting the crucible IOI laterally but permitting of 1ongitudinal expansion and contraction as caused by temperature variations of said crucible IOI. Said supports I 22 and I23 have each the strut-I25 carrying the longitudinal angle I26 by means of which the hood plate I53 is maintained substantially in contact with the apron slope plate I32 as later described.

An apron I28 made in sections of convenient length extends along the front of said crucible IOI being bolted to said crucible plate I01. An apron slope plate I32 is suitably secured to the outer edge of the apron I29 and extends downwardly at an angle adapted to the passage by gravity of discarded lump slag and has a sliding contact with the hood plate I53. The top surface or the apron I28 is curved parallel to the line 6| representing the path of the shovel 5 as it vbacks rabbled charge displaced on said apron I28 back to its smelting position in the area II (see Fig. 37). Enclosing the smelting length of the furnace I00 are the jackets I36 at each end thereof with suitable water circulating pipes for inlet and outlet (not shown). The jacket I36 has an extended top forming a dead-plate I39 which at its outer ends'is connected with the hood end plate I54, said dead-plate I39 being adapted to receive surplus charge from the charger 200 and the charge worked onto it by the rabbler 300 and the backer v400. The top surface of both said dead-plates I39 and the adjacent apron I28 are parallel with the line 6I representing the path of the backing shovel 4| 5 onjits backing stroke, said shovel 4I5 being adapted to sweep the dead-plate I39 thereby ejecting surplus charge from it through the chute I82 attached to the hood plate I49.

Over the back side of the crucible IOI are the conventional tuyre jackets I42 provided with the spaced openings I43 for admission of an air blast to the furnace I00 by conventional tuyeres and air blast supply system (not shown), said tuyere jacket I42 being provided with the water circulating pipes I44 for circulation of water through said jacket I42 in the usual manner. The jackets I 42 are retained in place on the crucible IN by the bolted clips I09 and at the top are connected with the hood back plate I48.

The furnace I00 is enclosed with a hood I46 with the draft outlets I41 through which a draft is maintained to draw off the gases from the operating furnace I00, said hood being made sufficiently gas tight as substantially to exclude the infiltration of outside air into said furnace. The hood I46 hasa back plate I48, a top plate I49. a top front plate I 50 engaging a sand seal I5I carried by a movable middle front plate I52 which movablysupports the lower front plate I53, said hood having the end plates I54 carrying the end extensions I55 each having a bottom slope plate I56, a top plate I51 and the side plates I58, said extension I55 opening into said hood I46 and at its outer end having the charger opening I59 normally closed by a door I60 which may be opened by means of the lever I6I, the link I62,

the lever I63 carried by the center pivot I64 and on its other end having the roller I65 adapted to contact the charger 200 so that as the latter goes through the door I60, it is automatically opened and remains so until the charger 200 emerges therefrom. The door I60 with the operating means just described is shown in Fig. 22 for the right hand end of the furnace I00 where the charger 200 enters, and the like extension I55 carrying like door I60 at the left hand end of the furnace I00 (not shown in detail) is substantially identical except that the means for opening said door comprising items ,I 6I to I65 inclusive are positioned to open said door I60 as the charger approaches same fromthe inside of the furnace I00 instead of from theoutside of said furnace as at the right hand end thereof.

The middle front plate I52 is supported by the backer 400 for longitudinal movement therewith and for each backer arm 4I1 said front plate I52 is provided with a dished section I61 having a slot I68 through which said arm H1 is admitted for its work in the furnace I00, said arm 4" carrying a curved seal plate 461 adapted substantially to seal said slot I68 irrespective of the swinging movement of said arm 1.

The lower front plate I53 is carried by the double flanged wheels I10 movable on a Z-bar I1I fixed on the lower edge of the middle front plate I52. Said plate I53 is divided into longitudinal sections about fifteen feet in length as later noted and each section is provided with the finger I69 adapted to engage in a hole of the bracket 3II attached to each of the rabbler cross-beams 304, whereby said plate I53 is imparted longitudinal movement in fixed relation with the rabbler 300. For each rabbler poker 3l5 the plate I53 is provided with a slot I12 through which said poker can work on the smelting charge in the furnace I00, and underneath each slot I12 the fulcrum piece 33I is rigidly supported by said plate I53 for the support of the furnace end of the rabbler poker 3I5. The slots I12 having a width but little more than the diameter of the poker 3I5 and being in the lower part of the furnace I00 where the draft is the least, no provision is shown for preventing the infiltration of some air through said slots although such means could readily be providedif desired. The plate I53 is provided with the inspection doors I13 by means of which the operator may observe the condition and the working of the furnace I00 and perform any incidental manual operations which it may require. Said doors I13 may be propped or maintained open to permit of a controlled admission of outside air to the furnace I 00 for the purpose of reducing the average temperature inside of said furnace. In the lower part of said plate I53 are suspended the swinging doors I14 normally closed and opened by the force of the discarded lump slag for the passage of which said doors I14 are adapted. The angles I15 and I16 extend longitudinally on the plate I53 which is further stiffened by the vertical angles I11, which have the horizontal part I18 terminating in the vertical part I19 movably contacting with the longitudinal angle I26 supported by the cross-member I25 of the crucible supports I22 and I23 which arrangement is adapted substantially to maintain a movable contact between the hood plate I53 and the apron slope plate I32.

The front plates I52 and I53 movable respectively with the hacker 400 and the rabbler 300, substantially contact with the end plate I54 at each end of the hood I46 and therefore said movable plates I52 and I53 extend a sufficient distance beyond each end plate I54 as required to maintain a contact therewith irrespective of the longitudinal movements of the hacker 400 and the rabbler 300, said extension being indicated in the plan of Fig. 21.

The hood I46 is supported from above by the hangers I carried by the building cross-beams 94 which hangers also carry the brackets I8I from the pivots IBIa for the support of the charger track angles 22I and 222 and permitting for the longitudinal expansion thereof..

Near each end thereof the back plate I48 connects with the outlet chute I82 provided with a freely swinging vertical gate I83 and adapted to receive the material swept from the dead-plate I39 by the backer 400 and pass said material through the cross-conveyor I84 which is of the conventional electrical vibrator type actuated by the electro-magnet I85 and carried on the supports I86, and delivers said material to the longitudinal vibrator conveyor I81 conventionally shown, which delivers through a chute I88 leading to a conveyor I89 leading to a bucket elevator I90 which discharges to the vibrator screen I9I where the finer screened material passes to a bin 262 while the coarser screened material is finally discarded through a chute I92.

The temperature inside the furnace hood I46 will rise to several hundred degrees Fahrenheit and said hood may be insulated appropriately to reduce radiation therefrom as a matter of comfort and for the benefit of the adjacent mechanical equipment, insulation also being possible for parts of the mechanical equipment when desirable.

The hood I46 will be provided for longitudinal expansion with the expansion joints I93, (see Fig. 19) having between adjacent parts of each hood plate the open space I94 of about one inch covered by the butt-strap I95 firmly attached to the plate of one part and adapted to slip over the like plate of the adjoining part, as shown in cross-section on the top plate I49 of Fig. 19 and in elevation on the back plate I48, said expansion'joints being put in each of the longitudinal hood plates I48, I49, I50, I52 and I53 at about fifteen foot intervals in the length of the same, the inspection door I13 being loosely hinged so as to work freely across said expansion joints. The hood plates I48, I49 and I50 will be supplied with adequate stiffening angles (not shown), and between the plates I48 and I50 will be suitably spaced strut-angles I96 (see Figs. 19 and. 20).

The charging system The charger 200 has a longitudinal frame 20I composed of a leftchannel 202 and a right channel 203 between which are carried a plurality of spaced sloping fiat plates 204, the bottom of one said plate overlapping the top of the next louver fashion. The plates 204 have a slope somewhat less from that of the angle of repose of the charge as it is dropped from the feeders 248, 249 and 250 to the charger 200, which slope may approximate a twenty percent grade, sloping downward in the direction in which the charger is moving as it decelerates for dropping its carried charge into the furnace I00. The closure plates 205 and 206 are welded to the channels 202 and 203 respectively thus making a water-tight space 205a and 206a respectively adapted to the circulation of water by means later noted.

The frame 20I is suspended from a plurality of spaced axles 201 carried by the wheels 208. The charger 200 is imparted longitudinal movement through its end beam 209 having a rope clamp 2I0 attached to a rope 2II operating over the idler sheaves 2I2, the left end sheave 2I3, the right end sheave 2I4, the tightener 2I5 and is driven by the winch 2I6 through the motor 2I1.

The motor unit 2I1 is preferably a direct-current compound-wound, variable speed four-toone ratio, reversible motor especially adapted for frequent quick starting and stopping provided with a solenoid brake 2I8, and having the automatic control panel 510 actuated by the power contactor 512 (see Fig. 36) for movement to the left toward the furnace I00 and the panel 51I actuated by the power contactor 513 for movement to the right away from said furnace, each said automatic panel being electrically interlocked with the other and equipped for pushbutton remote control, and having the shunt-field rheostats respectively 531 and 538 manually adjustable for controlling the speed separately in each direction of said motor 2". At'its lowest speed the motor 2l1 will be adapted to impart movement to the charger 200 to the right at a speed of about four feet per second under the control of the panel 5H and the contaotor 513, which movement is brought to a stop by the action of the solenoid brake 2I8 on said motor 2| 1 when the current is cut off same. At its highest speed said motor 2I1 will impart movement to said charger 200 to the left at a controlled speed up to about sixteen feet per second under control of the panel 510- and the contactor 512, which movement will be controllably decelerateti by the solenoid-brake 2I8 with said motor 2I1, said brake being rendered inoperative when current is supplied to said motor 2I1,

and by means of adjustable spring or dead-- weight pressure becoming operative instantly when the current is cut oil? therefrom.

The charger 200 is movably supported by the track angles 22I and 222 having a right end support 223, the intermediate supports 224, the bracket supports 225 on the feeder floor 226, and through the building being supported from the trusses 9| by hangers I and their pivotally carried extensions I8I, said pivots I8Ia being adapted to permit of the deflection of the lower end of the hanger I8l due to the longitudinal expansion by heat of the track angles 22! and 222.

The channels 202 and 203 are each cooled by water passing to the left end thereof through the pipes 221 enclosed in the spaces 205a and 206a respectively, said pipes each having a connection 228 with a riser 229 in a funnel 230. At the right end of the travel of the charger 200 the funnel 230 contacts with a movable arm 23I attached to a swivel pipe 232 connected with a fixed pipe 233 provided with the plug valve 234 with its handle 235 and the connecting link 236 attached to the swivel pipe 232 whereby said valve 234 is caused to open when the charger 200 reaches its right end extreme position as shown in Fig. 2 and thereby water is circulated through the spaces 206a and 205a and overflows from the connections 231 on each of said channels 202 and 203.

Between the louver-like plates 204 is the vertical space 24I and when loaded the plates will carry the charge somewhat as indicated in the shaded area 242, which charge has dropped from the feeders 248, 249 and 250, which feeders pass the charge through the shaded area 243 showing the heavier charge on the right hand side corresponding to the tuyere side of the furnace I00. The shaded area 244 shows the charge passing longitudinally under the cut-off gate 268 later described.

The belt feeders 248, 249 and 250 are substantially identical as further described for the feeder 248 which has a conveyor belt 25I supported on the idlers 252, a tail pulley 253 and a head pulley 254 all carried on the frame 255 by the feeder floor 226, said head pulley 254 being driven by a shaft 256 connected with a geared speed reducer 251 driven from a motor unit 258.

The posts 259 support the bins 260, 261 and 262 each having a back plate 263, side plates 264 and the front plate 265 provided with an opening 266a extending between the cheek plates 266 connected by a baffle plate 261 through which opening the charge or material carried in said bin may pass out under the control of the sector gate 268 carried from the pivots 269 by the levers 210 each having the front pivot 21I supported by a turnbuckle 212 suspended from the solenoid magnet 213 supported from the bin front plate 265. Each end .of said gates 268 has its support as described and is thereby separately adjustable as tothe height of the opening 260a left between it and the feeder belt 25I, the turn buckle 212 being adapted for ample manual adjustment and the solenoid 213 for a limited remote-control electrical adjustment by the manual operation of a switch 214 of which there is one conveniently located for each solenoid 213. Each of the bins 260, 26I and 262 has a feeder, respectively 248, 249 and 250, each arranged in like manner for delivering the charge in said bin by said feeder to the charger 200.

The motor unit 258 is preferably a direct-current compound-wound variable speed motor especially adapted for frequent quick starting and stopping and provided with its integral solenoid brake (not shown) and having an automatic control panel 280 adapted for operation manually and also from the control system 500, and having a shunt-field rheostat 28I manually adjustable for controlling the speed of said motor 258.

The rabbler and backer The rabbler 300 has a carriage 30I having the longitudinal channels 302 and 303 with wearing strips 3I0 supporting a plurality of spaced crossbeams 304 carrying the ends of the crank-shafts 325 and 326, and the cross-beams 305 supporting the middle of said shafts, all held square by a cross-bracing 306-, having also motor-supporting cross-beams 301 and 308 and end beam 309 adapted to receive the force imparting movement to said carriage 30I. Attached to each beam 304 is a bracket 3| I having a hole in which loosely fits the finger I69 attached to each longitudinal section of the hood plate I53 thereby holding said plate I53 in fixed relation for longitudinal movement with the rabbler 300.

A group of pokers 3I5 are each supported balljoint fashion by a shaft 3I6 carried by a pair of arms 3", each arm being pivotally supported by the crank pins 3I8 and 3I9 of double-throw cranks 320 and 32I respectively. Said cranks each have another pin 322 and 323 respectively located at ninety degrees from the pins 3| 8 and 3I9, and connected by a link 324 which together with the upper part of said arms 3I1 will always remain in a vertical position while being moved in a circular path by saidcranks 320 and 32I respectively keyed on the shafts 325 and 326 journalled near each end on the beams 304 and at a middle point on the beam 305, and having the counter-weights 321 counter-balancing the load carried by said cranks. The shaft 326 is driven by the gear 328 from the pinion 329 on a line shaft 330 journalled on the series of beams 304 and 305, said shaft 330 having a plurality of said pinions 329 adapted to drive the plurality of the shafts 326 for the groups of pokers 3I5. The poker 3I5 is supported at its furnace end (alternately) on the fulcrum 33I, and in another part of its stroke by the inner edge of the apron I28, and on its outer end by the shaft 3I6 operating with a clock-wise circular motion on line 51 thereby producing a rabbling motion adapted to break up the smelting charge as it occupies approximately the shaded area 1| (see Fig. 37) supported on molten metal normally substantially on line 12, thus displacing the charge to a posi- 'tion approximately underlying the line 13.

The shaft 330 is driven through its gear 334 and the pinion 335 by the geared speed reducer 336 and the motor unit 331 (both conventionally indicated) to operate the rabbler shaft M6 in its circular motion at a speed of about thirty revolutions per minute with variations generally not exceeding ten percent down and twenty percent up.

The motor unit 331 is preferably a direct-current compound-wound variable-speed four-toone ratio, reversible motor especially adapted for frequent quick starting and stopping provided with its integral solenoid-operated brake (not shown) and having an automatic control panel 544 (see Fig. 36) adapted for operation manually and also from the control system 500, said panel also having a shunt-field rheostat 535 manuallyadjustable for controlling the speed of said motor 331. Said motor 331. is provided with an auxiliary solenoid brake 338 with its automatic control panel 545 adapted for operation manually and also from the control system 500. Both the integral solenoid brake with the motor 331 and its auxiliary brake 338 are held operative by adjustable spring pressure and rendered inoperative when supplied with electric current in accordance with the customary practice. The said integral brake therefore becomes instantly operative when the current is cut ofi said motor 331 thereby rapidly decelerating same, and after a predetermined decelerating motion, the auxiliary brake 338 becomes operative thereby almost instantly stopping the motor with the pokers 315 in a predetermined position and all under the control of the control system 500. g

The rabbler carriage 30l is provided with fixed wearing strips 3l0 and is supported on a plurality of the double flanged wheels 34! and 343, the wheels 3 being mounted in fixed position on a support 342 carried on the beams 86 suspended from the truss 9| by the hangers 95 as part of the building in. Fig. 5; the wheels 343 being attached to and movable with the backer carriage 40l as therewith described. The rabbling frame channel 303 is provided with a coupler body 341 containing two sockets 348 and 349 through which the coupler pin 441 on the backer carriage 40! can be engaged. When said pin 441 engages in the socket 348 the rabbler 300 is in a position relative to the backer 400 for an operating cycle to the right, and when saidpin 441 engages in the socket 349 the rabbler 300 is in a relative position for an operating cycle to the left, the rabbler 300 in all cases being adapted to impart longitudinal movement to the backer 400 through the coupling pin 441.

The rabbler 300 is shown in Figs. 1 and 3 with three six-poker units making a total of eighteen operating pokers 3 l 5, and is longitudinally moved by the attached piston rod 352 of the hydraulic cylinder 350 carried by the support 35l. Water under uniform hydraulic pressure is to be supplied for the cylinder 350 operation through the pressure pipe 354 from a suitable hydraulic systern (not shown), waste water being suitably disposed of through the outlet pipe 355. Motion to the right is controlled by the inlet valve 351 and the outlet valve 358 simultaneously operated, and motion to the left by the inlet valve 358 and the outlet valve 360. These four valves are iden-- tical and are as diagrammatically indicated in Fig. 29 where the solenoid magnet 36l acts on the valve stem 362 to open said valve which is closed by the spiral spring 383 when the electric current is cut off. These valves consequently are quick acting with an absolute minimum of wear due to throttling effect. The speed control is affected by the valve 356, Figs. 1 and 3, which is diagrammatically detailed in Fig. 30. The threaded valve stem 364 is adjustable up or down by the nut 365 to pass water at a rate suitable for a slow speed movement. For a high speed movement the valve stem 364 is raised by the solenoid magnet 366 said stem being automatically returned to the lower position by the spring 361 when the electric current is cut off. Said valve 356 being always substantially open, the cutting action of the throttled water is distributed over hard extensive surfaces of the slow wear on which is immaterial. The pressure valves 351 and 358, controlling movements of the rabbler. may be provided with adjustable dash-pots (not shown) to ease the opening of said valves, and between the two ends of the hydraulic cylinder 350 may be placed pressure relief valves (not shown) which will cushion the stopping of the rabbler 300 by allowing water at excess pressure to escape from one to the other end of said cylinder, one pressure relief valve working in one direction being required for each of the directions of movement imparted by said cylinder.

The shaft 3l6 is provided with thesleeves 310 (see Fig. 34) with partly spherical outer surface each carrying a poker holder 3H for the poker 3l5, thereby permitting a variation in all directions of the angle of the axis of the poker 3| 5 relative to the axis of the shaft 3l6. The poker 3l5 has a flxed collar 312 which holds it longitudinally in the holder 311 provided with the shoulders 313 and 314 by which the poker 315 is retained at two spaced points by the pivoted and bolted caps 315. The collar 312 bears against the pressure relief spring 316 on its upper side, and against the removable U-shaped flller pieces 311 shown on the lower side and movable to the upper end of thespring 316 as the point of the poker 3 l 5 wears. The poker 3 l 5 is referably constructed of a double extra-heavy pipe closed at the lower or furnace end and at its upper end provided with a pipe-fitting cross 318 through outer end of which passes the tube 319 connected directly with the T 380, said tube 319 extending close to the lower end of the hollow poker M5 for purposes of circulating a cooling. fluid through said poker. The cooling fluid, preferably oil or air, is supplied and exhausted respectively through the longitudinal pipes 383 and 384. For each shaft 3l6 with its carried pokers 3l5, the swivel pipe connections 385 connect with one end of the shaft 3l6, its other end being connected through the flexible tube 386 to the longitudinal flexible tube 38l, the latter being connected through and between the crosses 318 whereby the fluid enters the pokers 3i5, leaving by the tubes 319, connected into the Ts 380 through and between which is connected the flexible tube 382 leading to the swivel pipe connection 381 and thence through the pipe 384 and the flexible tube 389 to a suitable circulating system (not shown). The flexible tube 388 connects from said circulating system to the pipe 383 described above.

The backer 400 has a carriage 40l with longitudinal channels 402 and 403 with wearing strips 0, supporting a plurality of vertical posts 404 tied together with bottom channel 405, all held square by cross-bracing 406 and having also motor-supporting beams 401 and 408. I A shovel 5 with supporting loops 4! 5a (see Figs. 31, 32 and 33) is pivotally carried on a pin 415 fixed in an operatingarm411 keyed to a longitudinal shaft 418. A compound lever 419 is pivotally supported on the pin 416 and its part 413a supports the back of the shovel 415, its part 41% is adapted to contact with a lug 411!) on the operating arm 411 thereby limiting the rotation of the lever 410. The part 419a is pivotally connected with a link 420 pivotally supported by a rocker lever 421 actuated by its lug 421a engaging for movement over to the left with the arm lug 411a. and having a detent 421b adapted to engage with a trigger 422 pivotally supported on a bracket 423 and contacting with a pressure spring 424- tending to maintain said trigger 422 in a vertical position, (see Fig. 18). The movable bar 425 supported in slots 428 in the posts 404 is movable laterally by a finger 421 attached to the arms 411 thereby disengaging the trigger 422 moving it into the position shown in Fig. 17 as the arm 411 swings to the lower and outer part of its stroke, and thereby the rocker lever 421 rotates from the position in Fig. 18 to that shown in Fig. 1'1 which, through the link 420 and the lever 419, permits the shovel 415 to rotate down on the line 83 of Fig. 3'1 to a position on the line 64 ready for-its efiective backing stroke into the furnace. The shovel 415 is shown in its working position relative to the arm 411 in Figs. 31 and 32 where the lever 413!) contacts with the operating. arm lug 411b thereby supporting the shovel 415 for its backing stroke whereby the rabbled charge approximately underlying the line 13 (Fig. 37) is swept back to its smelting position in the furnace in approximately the shaded area 11. As the shovel reaches its upper position on the line 61, the rocker lever 421 engages the trigger 422 thereby causing the shovel 415 to rotate on its supporting pin 415 as the operating arm 411 swings downward causing the lower edge ofthe shovel 415 to follow the line 82 until the shovel arrives in the position 51 whereupon it drops to the operative position 64 as previously described, and in which drop the edge of the shovel should clear the top surface of the apron sufficiently to avoid striking any of the smelting charge or agglomerate which may be rabbled thereon in the operation of the furnace.

The longitudinal shaft 418 carrying a plurality of the operating arms 411 is made of relatively large diameter thereby maintaining said arms 411 in substantially parallel operating relation due to the stiffness of the shaft 418 permitting of only a negligible amount of torsional twist, said shaft 418 being journalled on the post 404 and given an oscillating rotary motion by the rocker arm 420 moving between its position shown in Fig. 8 and its lower position on dotted line 58, said rocker arm 429 being provided with a slot 429a in which the crank pin roller 430 is moved on the circular path 80 by the crank 431 keyed to the shaft 432. The amplitude of the motion of the rocker arm 429 can be' varied if desired by changing the radius of the crank 431 and adjusting the angular position of said arm 429 relative to the shovel operating arm 411. The crank shaft 432 is driven through the gear 434 from the pinion 435 by the geared speed reducer 438 and the variable-speed motor unit 431 (both conventionally shown) adapted to drive the crank-shaft 432 at about twenty-seven revolutions per minute with a variation generally less than ten percent up or twenty percent down.

The motor unit 431 is in all respects similar to the motor unit 331 already described and has its Mounted below the posts 404 are the double-' flanged wheels 343 adapted to the vertical support of the rabbler channel 303 which in turn givesolateral support to the bottom of the backer 40 A longitudinal movement is given the backer 400 by the rabbler 300 through the coupling pin 441 working in the socket 448 supported on the angle 401, said pin 441 engaging with the coupier body 341 mounted on the rabbler channel 303 and having a socket 348 in which said pin 441 engages when the rabbler 300 and the backer 400 are both operating with a movement to the right, and the socket 349 with which said pin 441 engages when rabbling and backing are. proceeding to the left. The pin 441 is held down in an engaging position by the tension of a spring (not shown) and is raised for disengaging by the action of the solenoid magnet 440 carried by the angles 450 and 451 on the backer 400, said solenoid 449 having its automatic control panel 543 adapted for operation manually and also from the control system 500 by the contactor 553 (Fig. 36).

Connected in parallel with the solenoid 440 from its control panel 543 operated by the contactor 553, is a backer carriage solenoid brake 458 (see Figs. 1 and 5) which is a conventional solenoid-actuated band brake connected through the axle of one of the wheels 441 to prevent any movement of the backer carriage 401 when the coupling pin 441 is disengaged and the rabbler 300 is being moved to the alternative position rel-- ative to the backer 400. Said brake 458 is operated only when supplied by the electric current and is held inoperative by the action of a spring (not shown), and a plurality of said brakes 458 being used respectively with a plurality of said wheels 441 should more than one brake be found necessary.

The longitudinal shaft 418 is hollow and connected at each end respectively with the flexible tubes 451 (see Fig. 5) and 458 (not shown) connected respectively with the longitudinal pipes 383 and 384 on the rabbler 300 thereby providing .for the circulation of a fluid adapted to maintain the temperature circumferentially of said hollow shaft 418 sufliciently uniform as to avoid warping due to the heat radiated from the furnace 100, which heat strikes mainly one side of the oscillating shaft 410. v

When the rabbler 300 shifts to its alternative position with respect to the backer 400, the rabbler pokers 315 are stopped in a predetermined position as indicated by position 60 (Fig. 3'?) and. while the backer operating arm 411 continues its swinging movement, the shovel 415 moves only on the line 62 which is caused by permitting the trigger 422 to remain engaged with the rocker lever 421. Normally the'finger 421 (see Figs. 17 and 18) contacts the bar 425 as the arm 411 swings down thereby releasing the trigger 422, and when this release is to be avoided the bar 425 is longitudinally shifted to bring its spaced holes 425a opposite the spaced fingers 421, the

shifting of said bar 425 being effected by its rigid 1y attached slotted arm 46! engaging with the lower end of the lever 46i pivoted on the shaft 482 and rocked by the pull of the connected solenoid magnet 464, the return to normal working position being effected by the tension of a spring (not shown). The solenoid 464 is provided with its automatic control panel 548 which supplies current to said solenoid 484 when the power contactor 558 is closed by means indicated in Fig. 36. All details are to be proportioned so that when the relative positions of the rabbler 300 and the backer 400 are to be transposed, a clearance will be maintained between the poker 3|! and the shovel 5 as hitherto described and approximately as shown for the outer position of the shovel in 61 of Fig. 37.

The backer 400 carries a movable part ii! of the hood I46 provided with slots I88 through which the backer arms 4i! and the links 420 are admitted into the space inside the hood. The arm 4" has attached the radial angles 4" and 466 (see Figs. 16, 17 and 18) carrying a curved plate seal 46'! adapted substantially to seal the said slot I68 in the hood plate I62 irrespective of the motion of the swinging arm 4. The seal 481 and the angle 465 is provided with a slot 484 for the passage of the link 420.

The backer arms 4|! are relatively light but they might be balanced in their swinging motion by suitably placed counterweights or by spring tension. While the temperature inside the hood I46 to which these arms 4II may be subjected is variable with different ores and dependent somewhat on the running of the furnace as controlled by its operator, it is not expected that said temperature will rise to a point that will be harmful to said arms, but if unexpected extreme temperatures should arise, the arms could be made tubular in cross-section and provided with means for the circulation therein of a cooling medium somewhat after the fashion of the arrangement for the pokers BIS.

The control system An operation control system generally designated as 500 (see Figs. 25, 26, 28 and 36) is adapted for the automatic, timed and correlated control of the rabbler 300, the hacker 400, the charger 200 and the feeders 248, 249 and 250. All operations are efiected by electric motors, or electric solenoid magnets operating directly, or in-,

directly for the control of certain hydraulic valves, said motors and solenoids each having its conventional automatic control panel adapted for manual operation but normally actuated to produce motion while and as long as said panel receives current from a power relay contactor 550 and the like (see Fig. 36) Said power relay contactors are energized by relay current received from a relay switch, or more often a plurality of relay switches connected in series, each switch of any series being separately operated by a multipole relay Bill and the like energized from a terminal 5M and the like registering a relative position of some moving part, or a time period existing on an operation timer 5. The electrical return lines are to be considered as grounded and are not shown on the drawings.

The description given will relate to: first, the operating movements and motions, and reference to smelting charge positions; second, the time registering terminals 5M and 502 and the position registering terminals 503 to 5" inclusive in detail; third, the means actuated through the aforesaid terminals thereby starting and stopping the various motive means, as diagrammatically shown in Fig. 36; fourth, the control for the charger and feeders.

Fig. 28 diagrammatically shows: a shortened furnace Hill of a length suitable for a rabbler ill with two pokers II! and at each end having the dead-plates III, a backer 400 with two shovels I, the registering electric terminals "3 to ill inclusive to be suitably positioned on a building beam 86 (See Fig. 5), the terminals 501 and carried by the backer 400 and positioned apart from each other a distance corresponding to about twice the distance between the centers of the poker 3|! and the shovel 4|! in working position relative to each other, the terminal 49l fixed on the rabbler I" and adapted to contact with any of said terminals 503 to I as the rabbler 3" moves into appropriate position relative to same, and the terminal 492 likewise fixed on the rabbler I00 and adapted to contact with the backer terminal 501 to register relative positions of the rabbler 300 and the backer 400 for a left hand rabbling and backing operation, and likewise to contact with the backer terminal 508 to register for a right hand rabbling operation. The series of spaced lines 41 positioned relatively on the length of a section of the furnace I00 represent approximately the points at which a poker 3i! strokes up in a right-hand rabbling operation, relative to the like series of spaced lines 48 for a left-hand cycle, the lines 41 oi one cycle being substantially intermediate to the like lines 4! of an alternate cycle, thereby securing a substantially continuous scraping effect against the back of the crucible II of the furnace IN by two or more rabbling operations.

In Fig. 28 the position opposite Ii is that in which a left-hand operating cycle has been terminated, the rabbler and the hacker remaining completely stationary until a right hand cycle is initiated by the operation timer 5H whereupon the rabbler and the backer move and operate until they reach position 52, when the rabbler pokers 3|! are stopped in a pre-determined part of their motion, the backer coupler disengages and the backer brake becomes operative, the backer shovel 4| oscillates only on the line 62 (see Fig. 37) and the rabbler moves to the left, with a higher speed caused by increased opening of the valve 356, until the rabbler reaches position 53. Except that the pokers 3|5 still remain unoperated, the normally working backer and the rabbler move together at normal speed to position 54, the right-hand shovel 4|! of the backer sweeps any material from the right-hand deadplate I", and all movement and motion stops with the backer shovels at a pre-determined point later described. Promptly thereafter the charger Zlill deposits the charge in the furnace Hi0 and there ensues a mechanically quiescent smelting period in the furnace Hi0 until the operation timer initiates another operating cycle.

The left-hand backing and rabbling operation is in all respects similar to the right-hand operation, except with the corresponding movements respectively in the opposite direction. Position 55 shows the rabbler 300 with its rabbling work completed in a left-hand cycle and position I shows the rabbler 300 in transposed position relative to the backer 4" ready for a final movement back to position 5| which is at the end of the lefthand cycle and likewise at the beginning of the right-hand cycle.

Movement is imparted to the poker II! by its operating shaft Ill moving on the circular path 51 (see Fig. 37) which movement is always to be stopped in the part 58 of said circle 51, the working point of the poker 3l5 having been caused to move substantially on the line 59 and said poker occupying approximately the position shown on the position 60 when it is stopped.

The backing shovel 4| 5 moves inward along the line 6| (see Fig. 37) in its effective backing action and returns outward out of contact with the charge along the line 62 and suddenly drops along the line 63 to the starting position as shown at 64 (see Fig. 8). When the shovel 5 is stopped it will be approximately in the position 66 (Fig. '1) while the position 61 (see Fig. 3'1) is when the shovel H5 is ready to drop down the line 63. Motion is imparted to the shovel 5 through the oscillation of the rocker arm 429 from the position shown to the dotted position 68 by circular motion of the crank pin roller 430 on the line 69.

The smelting charge in the furnace I00 occupies approximately the shaded area 1 I, supported on top of the molten metal normally at about the line 12 and aproximately underlying the line 6| of the backing action of the shovel 5. When the charge is rabbled by the action of the poker 3|5 it is displaced from the area 1| and aproximately underlies the dotted line 13 from which position it is returned by the action of the backing shovel 4|5. An operation timer 5|4 (see Fig. 36) has its adjustable variable-speed mechanism to operate its rotor 5|5 at a speed generally between twenty and twenty-five revolutions per hour, said rotor 5|5 being connected at its center with the direct-current low-voltage relay bus 493, and from zero to one hundred and twenty degrees in its revolution contacting the terminal 50| for a right-hand operating cycle of rabbling, etc., and in like manner from one hundred and eighty to three hundred degrees (in the second half of its revolution) contacting the terminal 502 for a left-hand operating cycle.

The longitudinally movable rabbler 300 (see Fig. 36) has fixed on it the relay current fingers 49! and 492 receiving current from the relay bus 493 through a flexible connection. On a building beam 96 are suitably mounted the spaced terminals 503 to 506 inclusive adapted to receive current from the rabbler finger 49| as the movement of said rabbler brings said finger in contact with one of said terminals, said movements of the rabbler 300 being diagrammatically shown in Fig. 28 and hitherto described.

The rabbler contact finger 492 is adapted to contact with either of the terminals 501 and 508 carried in fixed position on the backer 400, the terminal 508 being positioned relative to the finger 492 for a cooperative rabbling and backing operation to the right, and the terminal 501 being correspondingly positioned for an operation to the left, along the furnace I00.

When the rabbler motor 331 (see Fig. 36) is to be stopped, the current will be cut off as the contact rotor 5|6 mounted on the rabbler crank shaft 326 contacts with the fixed terminal'5ll thereby delivering relay current through said terminal from the bus 493. The motor 331 will then be rapidly decelerated by its integral solenoid brake and as the decelerating crankshaft 326 brings the rotor 5|6 in contact with the terminal 5|2, the'auxiliary solenoid brake 336 will be applied, thereby almost instantly stopping said motor with the poker carrying shaft 3|6 in a position on the are 58 of Fig. 3'1.

When the backer motor 431 is to be stopped, the current will be cut oil as the contact rotor 5|6 mounted on the backer crank shaft 432 contacts with the terminal 509 thereby delivering relay currentthrough said terminal from the bus 493. 'The motor 431 will then be rapidly decelerated by its integral solenoid brake, and as the decelerating crank shaft 432 brings the rotor 5|8 in contact with the fixed terminal 5|0, the auxiliary solenoid brake 438 will be applied, thereby almost instantly stopping said motor with the backer shovel H5 in the position 66 of Fig. 7.

When the relative positions of the rabbler 300 and the backer 400 are to be shifted from position 52 (see Fig. 28) to position 53, or from position 55 to position 56, the backer shovel M5 is held latched-up to operate on the line 62 of Fig. 37 by the action of the solenoid 464 rendering inoperative the release of the trigger 422, said inoperative position of all said triggers 422 being registered by the contact finger 5|9 mounted on each trigger 422 closing a circuit through the contact pin 520, and having a set of said contact fingers and pins for each trigger 422, all sets being connected in series, as diagrammatically indicated in reduced number of three sets only in Fig. 36, by means of which, relay current from the bus 493 is delivered to the multipole relay The aforesaid terminals 50| to 5|3 inclusive are adapted to transmit low-voltage relay current through the lines 52| to 533 inclusive and respectively, to actuate the multipole relays 60| to 6|3 inclusive and respectively which relays are diagrammatically shown (see Fig. 36) spaced in a vertical row and adapted to actuate their respective draw-bars A to M inclusive, thereby in each case closing all the respective contact switches (or poles) connecting therewith and designated as A2, etc., in like manner. Said drawbars are held with switches open by springs 6|4 except when said relays are energized by relay current as hitherto described.

Parallel to said draw-bars A to M inclusive and below'same is the relay bus 493 connectingwith the spaced vertical relay lines 2 to 4| inclusive passing up across the non-conductive draw-bars A to M inclusive, and at certain intersections between the spaced horizontal draw-bars A to M inclusive and the spaced vertical relay lines 2 to 4| inclusive are the contact switches each having a designation by capital letter corresponding to that of the draw-bar A to M by which it is actuated, followed by a designation by a number corresponding to the number of the vertical relay lines 2 to 4| in which it is placed, as for example, A2 is the contact switch in the vertical line 2 actuated by the draw-bar A from the multipole relay 60| actuated-by current through the line 52| from the timer 5|4 by its contact 50| which initiates an operating cycle with the rabbler moving to the right, and all other of the contact switches of the multipole relays may be traced back in like manner from its designation (to be given) and the preceeding descriptions, or very readily by reference to the diagram of Fig. 36.

The said contact switches are as follows:

A2, A3, Al I, A|5, Al9, A20, A22, A24, A26, A28, A30, A32, A34, A31, A39, A40.

B6, B1, B8, BI4, Bl8, B2|, B23, B25, B21, B29, B3l, B33, B35, B36, B38, B4|.

C2, C4, C|0, C|2, Cl6, C20, C23, C24, C21, C28, C3|, C32, C35, C36.

D6, D8, D|4, DIS, 1).

E3, Ell, El5, El9, E40.

F5, F1, F3, FII, Fi1, F2|, F22, F25, F25, F25, F35, F33, F34, F31.

G3. G4, Gll, Gl2, GI5, Gl6, Gll, G35, G35. G45.

H5, H5. H5, Hl3, Hl4, Hll, Hl5, H31. H38, H4I.

I-35, I-3I.

L4, L9, Ll2, Ll3, LII, Ll'l, L25, L21.

Summing up.

Draw-bars A and B each operate sixteen contacts Draw-bars C and F each operate fourteen contacts Draw-bars D and E each operate five contacts Draw-bars H and I each operate ten contacts Draw-bars J and K each operate two contacts Draw-bar L operates eight contacts Draw-bar M operates six contacts On account of the easier understanding of the diagram in Fig. 36, I have shown the vertical relay lines 2 to 4| inclusive as thirty-nine separate lines whereas there are only about sixteen difierent groups necessarily used. The electrical expert will therefore readily understand that only the said reduced number of lines is essential provided opening relays are used between the upper terminals of said lines and the power contactors 555 to 555 inclusive and 512, all actuated thereby. However. as the relay current passing at any point through the control system is only that commonly handled by a push-button contact, the whole equipment is extremely small and easily taken care of and requires little attention whichever way it is made.

The power relay contactors 555 to 558 inclusive, 512 and 513 each have an upper main contact which closes to transmit current from the power bus 455 to the conventional automatic switchboard panels 545 to 548 inclusive, 515 and H, which panels are each adapted to start and maintain in operation their respective controlled motors or solenoids as long as said panels receive current from their respective connected power relay contactors, and thereafter stopping said motors or solenoids.

Said power relay contactors 555 to 555 inclusive and 512 (omitting 513) are each closed and opened by means of current supplied through the relay lines 2 to 4| inclusive (except the opening of contactor 512), all said contactors working on the same principle and the detailed working of the contactor 555 will be described as an example.

When the rabbler and backer are to be moved from position 5| (see Fig. 28), the vertical relay line 2 has its contact switches A2 and 02 concurrently closed, relay current is passed from the bus 453 to the line Hi to the coil 555:: of the contactor 555 thereby closing the upper power switch 55% and also its lower relay switch 555e, which latter continues to supply relay current to the coil 555a through the normally-closed opening-relay 565 from the relay bus 493 irrespective of the opening of said switches A2 and C2; and when position 52 (see Fig. 28) is reached, the contactor 555 will be opened by the concurrent closing of the switches (one in this case) in the vertical line 5 thereby supplying current through the line 54| to the opening-relay coil 565a thereby opening its switch 565c thereby interrupting the relay current to the contactor 555 causing the latter to open its switches 55511 and 5550, to

'for positions 52 and 55 respectively;

remain open until again closed by means as first described acting through the line "I. Having described the mode of operation 01' the power relay contactors similar to the contactor 555, the operating connections for, and the purpose of each one of these said contactors will now be described.

The contactor 555 is closed by the line 52| connected to the lines 2, Land 4 for positions 5|, 53 and 55 respectively; and'is opened by the relay 555 by the line 54| connected to the line 5 for positions 52 and 54'. and to line 5 for position 56; thereby actuating the panel 545 for the control of the solenoid hydraulic valves 351 and 353 for imparting a right-hand movement to the rabbler lll.

The contactor "I is closed by the line 622 connected to the lines 1', 5 and 3 for positions 54, 56 and 52 respectively; and is opened by the relay -55| by the line 542 connected to the line l5 for positions 55 and 5|, and to line H for position 53; thereby actuating the panel 54| for the control of the solenoid hydraulic valves 358 and 365 for imparting a left-hand movement to the rabbler 355.

The contactor 552 is closed by the line 523 connected to the lines l2 and I3 for positions 55 and 52 respectively; and is opened by the relay 562 by the line 543 connected to the lines l4 and I5 for positions 55 and 53 respectively; thereby actuating the panel 542 for the control of the solenoid regulating valve 355 causing it to open wider for the morerapid travel or the rabbler 355.

The contactor 553 is closed by the line 624 connected to the lines l6 and I1 for positions 55 and 52 respectively; and is opened by the relay 563 by the line 544 connected to the lines l8 and IQ for positions 55 and 53 respectively; thereby actuating the panel 543 for the control of the solenoid 443 for disengaging the coupler pin 441 which interlocks the rabbler 355 and the hacker 455 for movement together, and it also controls the solenoid brake 456 causing it to be operative while the rabbler 355 is moving and the backer 455 is held stationary.

The contactor 554 is closed by the line 625 connected to the-lines 25 and 2| for positions 5| and 54 respectively; and is opened by the relay 564 by the line 545 connected to the lines 22 and 23 thereby actuating the panel 544 for the control of the motor 331 imparting motion to the rabbler pokers 3 l 5.

The contactor 555 is closed by the line 526 connected to the lines 24 and 25 for positions 5| and 54 respectively; and is opened by the relay 565 by the line 545 connected to the lines 26 and 21 for positions 52 and 55 respectively; thereby actuating the panel 545 for the control of the auxiliary solenoid brake 338 operating with the motor 331 causing the partly decelerated motor to be quickly stopped.

The contactor 556 is closed by the line 621 connected to the lines 28 and 29 for positions 5| and 54 respectively; and is opened by the relay 566 by the line 641 connected to the lines 35 and 3| for positions 54 and 5| respectively; thereby actuating the panel 545 for the control of the backer motor 431 imparting motion to the hacker shovels 4| 5.

The contactor 551 is closed by the line 628 connected to the lines 32 and 33 for positions 5| and 54 respectively; and is opened by the relay 561 by the line 548 connected to the lines 34 and 35 for positions 54 and 5| respectively; thereby actuating the panel 541 for the control of the auxlliary solenoid brake 433 operating with the motor 1':

' contact with the terminal 431 causing the partly decelerated motor to be quickly stopped.

The contactor connected to the lines 38 and 31 for positions 55 and 52 respectively; and is opened by the relay 558 by the line 848 connected to the lines 38 and 38 for positions 58 and 53 respectively; thereby actuating the panel 548 for the control of the solenoid 484 rendering the release of the triggers v422 inoperative.

The contactor 512 is closed by the line 838 connected to the lines 48 and 4| for positions 53 and 58 respectively; and is opened by the relay 514 connected to the line 831 (see Fi 26).

Near the right hand end and on one side of the charger 288 is a lug 585 (see Fig. 2'7) adapted to contact with an operating lever 588 of the switch 5! causing the blade 582 to move into 583 thereby delivering current from the connected relay bus 493 to said terminal. As soon as the lug 585 moves out of contact with the lever 588, the switch 58l returns to its neutral position by the tension of a spring not shown. The terminal 583 may be located to one side or the other of the switch 58I depending on the direction of travel of the charger 288 at the time when the desired contact is to be made. There are eight switches 58l respectively connected with the terminals 841 to 848 inclusive energizing the relay lines 831 to 838 inclusive and each of the switches 58l are appropriately located on the charger track 222 (see Fig. 26) relative to the passage along same of the charger lug 288 so as to cause the related operating effect to take place at the predetermined point in the travel to the left or to the right of the charger 288.

The line 83! connects to the terminal 841 appropriately located near the furnace I88 where deceleration of the' charger 288 is to begin,- thereby appropriately spreading its carried charge in said furnace, said terminal 8 being connected through the line 83! to actuate the stopping relay 514 (see Fig. 86) for opening the contactor 512 as above referred to.

The contactor 513 also receives relay current from the line 831 and is opened by the stopping relay 515 actuated by the line 832 connected to the terminal 842 located near the right-hand end of the charger track 222, said contactor 515 actuating the panel 51! controlling the motor 2" for the right-hand movement of the charger 288. Panels 518 and 511 are conventional automatie control panels and are electrically interlocked so that motor-starting current from the panel 51l is not delivered until the motor 211 has been substantially stopped under the control of the panel 518.

The terminal 643 (see Fig. 26) through the line 833 connects to a starting relay 851 (see Fig. 25) for closing the power contactor 852 controlling the conventional automatic panel 288 for the operation of the motor 258 driving the feeder 248, the speed of which is controlled through a shunt-field rheostat 28l on said panel, said terminal 643 being positioned on the charger track 222 relative to the moving charger lug 585 so as to cause the feeder 248 to start delivering charge to the charger 288 .at the proper point in its travel to the right away from the furnace I88. The terminal 848 through the line 838 operates the stopping relay 855 causing the feeder 248 to be stopped as the charge receiving length of the charger 288 passes to the right of said feeder 248 for which purpose said 558 is closed by the line are terminal 848 is appropriately positioned near the right end of the charge track HI and is separated from the terminal 843 by a-dlstance substantially equal to the length to be charged on the charger 288. In like manner the terminals 844 and 845 operate to start the feeders 248 and 258 driven by their respective motors 258 not separately shown, and the terminals 841 and 848 serve to stop said feeders through means izdeantical in principle with those for the feeder The conventional automatic control panels 548, 5, 542, 544 and 548 (see Fig. 36) are preferably provided with a time relay on the starting arrangement adjustable up to about two seconds delay in starting after the controlling power contactor as 558, etc., has closed. 0n panels 544, 548, 518 and 5H are shown the shunt-field rheostats respectively 535, 538, 531 and 538, which are manually adjustable for governing the speed of the related motors.

For a furnace of the approximately ninety foot length illustrated, the electric motor required may be about fifteen horsepower each for the charger, the rabbler and the backer, and five horsepower each for the three feeders shown. Each of these motors is to be started and stopped for each of the forty to fifty operating cycles per hour, and solenoid-operated band brakes have been specified for the stopping. The wear on these brakes may be reduced to a negligible amount by providing with said motors and.

their respective automatic control panels arrangements for dynamic braking whereby in decelerating a motor an electric current is generated and passed through a rheostat, the adjustable resistance of which determines the degree of the braking effect produced, all in the mode commonly used in the electrical arts. Such provision is therefore desirable for the purpose of minimizing the wear on the brake bands. In addition to the automatic controlling means herein described, the panels of all motive means will provide for the manual operation of the same, as is generally customary.

Mode of operation I will now describe my preferred general mode of operation of the furnace and equipment herein specified, this description being supplemented in detail at various other places in the specification.

The temperature controlling-fluids will first be caused to circulate through all adapted parts of the furnace, the rabbler, the backer and the charger from suitable sources (not shown). A light wood fire will then be built in the crucible I81 which will be slowly heated to a temperature hot enough to melt lead when the latter will manually be charged to the crucible until it is substantially full of molten lead. By manual control of the charger 288 and suitable cooperating control of the feeders 248, 248 and 258, coke breeze and ore will be slowly charged to the furnace to be ignited by the remaining wood fire, the air-blast having been turned on through the tuyere openings I43 at a suitable time, (from a blast system not shown), the suction fans (not shown) having been started for drawing away from the furnace the gas being evolved. The rabbler 388 and the backer 488 may be put into irregular operation under manual control rather than by timed control as the furnace is being brought into regular smelting condition, and when the smelting charge is gotten into normal 

